This invention relates to a package containing a tackless or nonblocking hot melt adhesive and to the method for producing such packaging wherein a selected wax coating material and a low pressure, melt blow application technique are used.
Hot melts adhesives which are generally applied and distributed while in the molten or liquid state are solid at room temperature. Typically, these adhesives are provided in the form of blocks and because of the nature of these materials, particularly the pressure sensitive hot melts, there are problems associated with handling and packaging them. Blocks and other forms of these materials not only stick or adhere to hands or mechanical handling devices and to each other, but they also pick up dirt and other contaminants. Additionally, certain applications which require high tack formulations result in blocks that will deform or cold flow unless supported during shipment. The need and advantage of providing a tackless or non-blocking adhesive is therefore quite apparent and various ways of accomplishing this have been tried and developed over many years.
Japanese Patent Bulletin 48-103635 published Dec. 26, 1973 discloses a granular adhesive which is tacky at room temperature and coated or enveloped with a non-tacky, hot meltable material that is the same type or is miscible or mixable with it.
French Patent 2,544,654 published Oct. 26, 1984 discloses forming a tackless hot melt by adding molten hot melt to a mold containing a preformed support layer having a transfer film thereon and which is compatible with the hot melt.
U. S. Pat. Nos. 4,748,796 issued Jun. 12, 1988 and 4,755,245 issued Jul. 5, 1988 disclose forming a protective coating for an adhesive material by electrostatically coating a mold or cavities with a powder screen and then pouring hot melt into the mold.
French Patent 2,601,616 published Oct. 22, 1988 discloses forming blocks of hot melt pressure sensitive adhesives by casting the pressure sensitive adhesive into molds precoated by spraying with a film of non self-sticking hot melt material thereby forming a fusible non-tacky veil around the pressure sensitive block.
Various other methods of making tackless hot melt adhesives have also been developed. However, despite all these techniques which include many alleged compatible, non-adhesive coating materials and a number of different application systems and equipment, there are still problems in producing a thin, continuous, adherent coating which is completely compatible with the hot melt adhesive and most important is not brittle and will not flake or rub off during handling.